* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    width: 100%;
    height: 100vh;
    overflow: hidden;
    display: grid;
    place-items: center;
}

#grid {
    width: 80vw;
    height: 80vh;
    display: grid;
    grid-template-columns: repeat(10, 1fr);
    gap: 5vw;
    padding: 5vw;
    border: 8px solid #878787;
    overflow: auto;
}
.item {
    width: 18vw;
    height: 18vw;
    display: grid;
    place-items: center;
    font-size: 80px;
    font-weight: 700;
    border: 2px solid #878787;
    user-select: none;
}
.item[data-selected = 'true'] {
    background-color: rgb(174,229,255);
}